The present invention relates generally to a safety brake device for the load receiving means of vertical conveying equipment, including at least one brake wedge, which is arranged in a housing and which on triggering of a braking action acts on a guide rail of the conveying vehicle, and an abutment, which limits the stroke of the at least one brake wedge and thus limits the maximum braking force during the braking process. Moreover, the invention relates to a method of adapting the braking force of this safety brake device to the masses which are to be braked and which act on the load receiving means.
Safety brake devices as described above are used for, for example, passenger elevators, goods elevators and cages in mine conveying installations, wherein the braking process is usually triggered by a limiter cable, which acts on the brake wedge, of a speed limiter when a permissible travel speed is exceeded.
There is shown in the Austrian patent specification No 297260 a safety brake device according to the description above, in which a sliding guide, which is fastened to the elevator car and consists of angle girders, is provided for a wedge housing. The wedge housing has a recess which extends conically in a vertical direction and in which two brake wedges are arranged and surround the guide rail of the elevator with a play. The brake wedges are mounted on balls in grooves of the recess to be rollable, so that only a low rolling resistance arises at the wedge surfaces of wedge housing and brake wedges during movement thereof. The two brake wedges can be moved by a double lever seated on a shaft which is rotated by way of a lever of the limiter cable of a speed limiter. When the permissible speed of the elevator is exceeded, the brake wedges are pressed against the guide rail and initiate the braking process. A support bracket, against which the wedge housing is supported by way of plate springs, is fastened above the wedge housing to project from the car. Setting screws serving as abutments for the brake wedges and secured by nuts are arranged at the support bracket. During the braking process the brake wedges are drawn into the wedge housing to an extent corresponding with the thickness of the guide rail. The braking forces thereby arising have the effect that the wedge housing is raised against the plate springs until the brake wedges abut against the setting screws, whereby a further increase in the braking forces is prevented.
The safety brake device described in the foregoing has the disadvantage that in the case of different masses to be braked, different retardation values are generated at the load receiving means. In the case of large loads in the load receiving means a too small retardation of the load receiving means can thus arise and in the case of small loads an unacceptably high retardation of the load receiving means can arise and thus lead to harm to persons and property.